Interchange server for modular application collaboration

ABSTRACT

In general, in one aspect, the invention provides a modular application collaborator for providing inter-operability between applications including a plurality of connectors for communicating with a like plurality of applications and an interchange server. The interchange server includes an application collaboration module and service module. The service module transfers messages between connectors and the application collaboration module. The application collaboration defines the inter-operability between two or more applications. The interchange server service module includes a transaction service and an error service. Transactions are executed in the application collaboration module and the transaction service records each action and a compensating action for undoing an associated action. An error service monitors for errors in the interchange server, and, upon detection of an error, stops the execution of a transaction and initiates the execution of any required compensating actions to undo the interrupted transaction. The compensating transactions may be executed at the connectors and are not required to be overseen by the interchange server.

[0001] This application is a Continuation in part of application Ser.No. 08/780,593, filed Jan. 8, 1997.

[0002] The present invention relates generally to computing systems, andmore particularly to a method and apparatus for providing collaborationbetween applications operating in an information system.

BACKGROUND

[0003] Corporations have spent billions of dollars a year to implementcustom, standalone information systems that address specific businessdomain functionality requirements such as accounting, payroll,manufacturing, and distribution. By creating these separate, standalonesystems, each individual section of the business process became isolatedfrom the others.

[0004] Over time, Corporate Information Technology (CIT) departmentsbegan shifting away from in-house development of these custom systemsand have attempted to minimize costs by purchasing enterpriseapplications on the outside. Enterprise applications are more generic,providing general business functionality in a pre-packaged product.Typically, enterprise applications include heterogeneous combinations ofapplication systems, hardware platforms, operating systems, third- andfourth-generation languages, databases, network protocols, andmanagement tools. While these applications bring tremendous benefits tothe companies that implement them, on an enterprise level, they onlyexacerbate the proliferation of “process islands” because they are notreadily integratable.

[0005] Stand-alone enterprise applications provide powerful tools forhandling many business processes. However, some functionality is oftenduplicated in separate applications, driving up the cost when bundlingenterprise applications. Custom functional integration betweenenterprise applications, while desirable, is generally cost prohibitive,and defeats the benefits of the make-versus-buy decision to purchase theenterprise application in the first place. Tool and middleware vendorsoffer solutions for data integration, but not function integration, andeven those solutions require significant custom coding to implement.

SUMMARY OF THE INVENTION

[0006] In general, in one aspect, the invention provides a modularapplication collaborator for providing inter-operability betweenapplications including a plurality of connectors for communicating witha like plurality of applications and an interchange server. Theinterchange server includes an application collaboration module andservice module. The service module transfers messages between connectorsand the application collaboration module. The application collaborationdefines the inter-operability between two or more applications. Theinterchange server service module includes a transaction service and anerror service. Transactions are executed in the applicationcollaboration module and the transaction service records each action anda compensating action for undoing an associated action. An error servicemonitors for errors in the interchange server, and, upon detection of anerror, stops the execution of a transaction and initiates the executionof any required compensating actions to undo the interruptedtransaction. The compensating transactions may be executed at theconnectors and are not required to be overseen by the interchangeserver.

[0007] Each connector includes an application interface, a businessmodule and interchange server interface. The application interfaceincludes an API manipulator for receiving and transferring data andmethods between a connector and its associated application. The businessmodule includes business methods and transforms for manipulating datafor transfer between an associated application and an applicationcollaboration module. The business module may include a filter mechanismfor filtering events received from an application to match requestsreceived from a collaboration. The interchange server interface allowsfor data transfer between a connector and an application collaborationmodule. The interchange server interface may include a proxy service foroverseeing the execution of compensating events at the connector level.

[0008] One advantage of the invention is that it allows businesses tosignificantly improve efficiency and productivity by integrating relatedfunctionality.

[0009] Other advantages include efficient resource management at thecollaboration level by proxy execution of compensating transactions andfiltering at the source. The transaction system is not required to beburdened with overseeing the execution of compensating transactions whena fault is detected. Rollback may be initiated and execution ofcompensating transactions may be delegate to the connector level. Inthis way, each connector acts as a proxy for the transaction server forits own respective application. The transaction system may maintainoverall responsibility for the rollback operation to allow forsequencing of transactions between differing applications, or mayrelinquish control to the individual proxies. Filtering of unwantedevents at the source connector level frees up collaboration and systemresources resulting in only the transfer of requested events between agiven connector and a collaboration.

[0010] Other advantages and features will be apparent from the followingdescription and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a schematic block diagram of a modular applicationcollaborator according to one embodiment of the present invention.

[0012]FIG. 2 is a flow diagram for a simplified collaboration accordingto one embodiment of the present invention.

[0013]FIG. 3 is a schematic block diagram of an interchange serveraccording to one embodiment of the present invention.

[0014]FIG. 4 is flow diagram for the operation of an event publicationand subscription service according to one embodiment of the presentinvention.

[0015]FIG. 5 is flow diagram for the operation of a transaction serviceaccording to one embodiment of the present invention.

[0016]FIG. 6 is flow diagram for the operation of an interchange serveraccording to one embodiment of the present invention.

[0017]FIG. 7 is a flow diagram for a service request performed by aninterchange server according to one embodiment of the present invention.

[0018]FIG. 8 is a flow diagram for a shutdown procedure for aninterchange server according to one embodiment of the present invention.

[0019]FIG. 9 is a schematic block diagram of an applicationcollaboration module according to one embodiment of the presentinvention.

[0020]FIG. 10 is a schematic diagram showing ordered message flows for asimple application collaboration according to one embodiment of thepresent invention.

[0021]FIG. 11 is flow diagram for creating an application collaborationaccording to one embodiment of the present invention.

[0022]FIG. 12 is a flow diagram for an application collaborationaccording to one embodiment of the present invention.

[0023]FIG. 13 is a schematic block diagram of a connector according toone embodiment of the present invention.

[0024]FIG. 14 is a flow diagram for the operation of a connectoraccording to one embodiment of the present invention.

[0025]FIG. 15 is a schematic block diagram of an administrative toolaccording to one embodiment of the present invention.

[0026]FIG. 16 is a block diagram for a connector development kitaccording to one embodiment of the present invention.

DETAILED DESCRIPTION

[0027] Referring now to FIG. 1, the architecture for a modularapplication collaborator 10 includes an interchange server 20 having oneor more connectors 30, and one or more application collaboration modules40, administrative tools 50 and development tools 60. Coupled to eachconnector 30 is an application 70.

[0028] Interchange server 20 is a distributed application server thatprovides an object oriented run-time platform for all components. Italso provides mechanisms to manage, configure and control components andprovides all of the reliability, availability, and serviceabilityfeatures (the RAS features) found in a typical server environment. Anobject component can reside in any interchange server within the sameadministrative domain. An administrative domain is a suite ofinterconnected connectors, application collaboration modules andinterchange servers. Multiple cooperating interchange servers can run ondifferent platforms. Platform in this case means any base softwareenvironment, including operating systems, databases (if necessary),and/or middleware.

[0029] Connectors 30 enable applications to communicate with interchangeserver 20. Connectors 30 handle all the details of interfacing withapplications 70, and provide an object-oriented interface to representthe application in the interchange server's object and data model.Connectors 30 communicate with applications 70 and provide a schema forinteracting with other applications in the interchange server'sobject-oriented model. Connectors can be thought of as having two ends.An “interchange-end” is an object-oriented proxy schema for theapplication's data and methods. An “application-end” is a driver for theapplication's APIs. In other words, the connector's interchange-endpresents a “virtual” object interface to the interchange server for thedata and methods (behavior) that reside in the application. To allowapplication collaboration modules to be re-used across connectors, thevirtual object interface presented by the interchange-end of theconnector is similar for connectors having the same application classbut which are produced by different vendors. The application-end of aconnector 30 is concerned with transferring information from application70 to the virtual objects and with propagating changes (requests forchange) made to the virtual objects back to application 70. Theapplication-end of connector 30 also contains vendor specific logicrequired to manipulate the vendors APIs. Connectors are application andvendor-specific.

[0030] Application collaboration modules 40 provide the specificintegration business logic and process flows required to integrate twoor more applications 70. Application collaboration modules 40 containthe re-usable part of the integration business logic, whereas, theapplication specific piece of the participating business logic is storedin connectors 30. An application collaboration module 40 requires aninterchange server 20 and an appropriate connector for each application70 participating in a collaboration. Application collaboration modules40 are specialized objects that coordinate communication and processflows between connector objects. Any application collaboration module 40executing in the interchange server 20 will see only the interchange-endof any connector 30. Application collaboration objects implement thebusiness interactions in terms of message exchanges between theinterchange server's services (which are objects), the participatingapplication's connector objects and other application collaborationobjects.

[0031] Administrative tools 50 provide a set of tools and interfaceswhich allow end-user customers to install, configure, control andmonitor interchange server 20 and connectors 30.

[0032] Development tools 60 provide a set of tools and libraries thatallow customers to develop their own application collaboration modulesand connectors. Tools are driven from meta-data in the interchangeserver's objects. Meta-data is a term used to describe the informationwhich characterizes the data, and is sometimes referred to as the datadefinition.

[0033] Applications 70 include various business applications supportingaccounting, billing, customer service, payroll and other businessprocesses. Application clients interact with an associated application70 using the application's user interface. Alternatively, applications70 may be non-business applications. Inter-operability between theapplications 70 is defined in an application collaboration module 40.

[0034] For example, a simplified business inter-operability functioninstituted in an first application collaboration module may requirereceiving data from a first application and writing a portion of it in anew format to a second application. A flow diagram for the simplifiedbusiness inter-operability function is shown in FIG. 2. Referring now toFIGS. 1 and 2, upon initialization, the first application collaborationmodule 40, and its associated (first and second) connectors 30 areinstalled in the interchange server 20 (100). The first applicationcollaboration module 40 provides a business interoperability functionthat includes at least a trigger (e.g., the receipt of information fromone or more applications) and a transaction (e.g., the writing of thenew data to one or more applications) responsive to the trigger. Thefirst application collaboration module 40 subscribes to an event basedon the trigger for the particular business interoperability function(102). In this example, the event is triggered by the receipt ofinformation at a first connector associated with the first application(103). Based on information received from the first application, theapplication-end of the associated connector passes data to theinterchange-end of the first connector (104). The interchange-end offirst connector transforms the information into the interchange formatobject and publishes the event (receipt of the information or trigger)(105). The event is delivered in the form of an object generated by thefirst connector to the first application collaboration module thatsubscribed to the event (or to any application collaboration module thatsubscribed to the event or that requested the data) (106).

[0035] Thereafter, the first application collaboration module executesits associated business inter-operability function and generates anobject for transmission to the second connector (108). The object itselfis delivered to the second connector (109), which in turn transforms theobject (data and methods) into the appropriate format (by theinterchange-end of the associated connector) and initiates the desiredfunction in that connector's associated application (by the applicationend of the connector) (110). The details associated with thecollaboration process will be described further below in associationwith the detailed descriptions for the individual components.

[0036] Interchange Server

[0037] Referring now to FIG. 3, an interchange server within a singleadministrative domain can be viewed as a bus into which various systemcomponents are plugged. Interchange server 20 includes applicationcollaboration module interfaces 200, connector interfaces 202, externalinterfaces 203, a configuration tool interface 204 connected toconfiguration tool 205, set-up tool interface 206 connected to set-uptool 207, system management interfaces 209 and a plurality of servicemodules 208.

[0038] Configuration tool 205 allows a user to enable and/or changeapplication collaboration module and connector properties. Setup tool207 installs, removes and configures application connectors in aninterchange server. System management interfaces 209 support industrystandard (SMS/SNMP) administration interfaces and provide a managementinterface to the interchange server's components. External interfaces203 allow tools and other external agents to access and control objectswithin interchange server 20.

[0039] Interchange server 20 is a component-oriented object executionenvironment for supporting the execution needs of application connectors30 (FIG. 1) and application collaboration modules 40 (FIG. 1). Itdefines a base object model of objects and components, which function aslarge grained container objects. Application connectors andcollaborations are implemented in terms of this base model and are largegrained containers within the interchange environment. This allowsconnectors and application collaboration modules to have powerfulinterfaces derived from the base model, while simultaneouslyencapsulating the details of their implementation within that individualcomponent of the interchange server.

[0040] Components are large-grained objects which contain other objectsand which can be loaded in via a DLL (dynamic linking and loading) atrun-time. Objects and components are defined in terms of theirinterfaces which are strictly separated from their implementations.Components are named through a name service 230 and found in a registry232.

[0041] Connectors are a component that acts as a proxy for anapplication. Connectors manage connector objects (also called virtualobjects) which are typically proxies for entities within theapplication. Application collaboration modules are objects which live inthe interchange server and can be dynamically registered orde-registered. Application collaboration modules create or manageobjects as needed. An application collaboration module can be viewed asa sub-component within interchange server 20 which uses the same baseobject model as the interchange server. Everything in the interchangeserver is expressed in terms of the base object model. The base objectmodel defines objects and the mechanisms for describing them. The baseobject model provides object orientation, distribution, locationindependence, and an ability to implement objects on the supportedplatforms.

[0042] Objects interact via events and messages. Event subscriptionservice 235, event publication service 236 and messaging service 242 arethe fundamental mechanisms by which application collaboration objectsinteract with connector objects. The interchange server 20 providesobjects with “services”.

[0043] The services provided by service modules 208 in interchangeserver 20 are those required by the connectors and applicationcollaboration modules to carry out their integration tasks. In oneembodiment of the present invention, the services are depicted asmodules on a bus and include name service 230, registry service 232,event service 234 including subscription service 235 and publicationservice 236, repository 238, dynamic loading service 240, messagingservice 242, rules engine service 244, data transformation service 246,transaction service 248 and error and exception service 260. Theinterchange server services include the capability to add and removeconnectors and collaborations dynamically, to test new configurations,to manage resources efficiently, to allow for smooth upgrades and torecover gracefully from hardware and software failures. Interchangeserver services are built out of the base object model and include allthe generally useful features that the interchange server's componentsrequire.

[0044] Interchange server 20 includes a registry service 232 tocoordinate the interchange server's startup processing and allow objectsto find other objects by name. This includes dynamic registration of newobjects as they become available. Dynamic registration allows a newapplication collaboration module to register itself. Dynamicregistration also enables other clients to locate a new collaborationwhen it comes online. Registry service 232 stores meta-data associatedwith any component in repository 238 which can be accessed by othertools in the interchange server.

[0045] Dynamic loading service 240 loads the run-time pieces of thecomponents and executes them without having to re-compile or re-link theinterchange server 20.

[0046] Event service 234 provides a publish and subscribe notificationmechanism. Event service 234 de-couples information providers frominformation consumers. The notion here is that application collaborationobjects may wish to subscribe to certain business objects/events thatare published by certain connectors without knowing the intimate detailsabout which connectors are publishing which objects. The event deliveryand subscription service includes subscription receipt (for an event),storage of the subscription, receipt of an event, event notification andobject transfer (result) associated with the event for each object(application collaboration module, connector, or interchange server)that subscribed to the event. The event service includes a subscriptionservice 235, including a subscription list, and a publication service236.

[0047] Referring to FIGS. 3 and 4, in the process of publishing andsubscribing to an event, a subscription is received from an object(connectors, collaborations or interchange servers) (400). Thesubscription service 235 stores the subscription in a subscription list(402). Upon receipt of an event notification (404), the publicationservice checks the subscription list to determine if there are anyobjects which have registered an interest in the received event (406).If an object has subscribed to the event, then the publication servicedelivers an object associated with the event notification to each objectin the subscription list requesting notification of the particular event(408).

[0048] Referring again to FIG. 3, messaging service 242 providesasynchronous execution semantics for geographically distributedcomponents. Messaging service 242 includes a reliable queuing andmessaging facility to allow interchange server 20 to support anasynchronous transaction model. Furthermore, the reliable deliverymechanism allows message requests to be persistently queued (insequence) to the participating component if the participating componentis unavailable. When the component starts up again, it processes anyoutstanding messages by getting them from the underlying persistentqueues. In one embodiment, the publish and subscribe services are builton top of the messaging service to provide an event service whichtranscends all process, system and geographical boundaries of theparticipating components.

[0049] Rules engine service 244 has two aspects, a definition aspect andan execution aspect. The definition aspect ties in with the definitionof a rule and the execution aspect consists of evaluating such rulesduring execution. Application collaboration modules use this service fordefining and evaluating the business rules that are enforced within theapplication collaboration module. Connectors also use this service whenevaluating business conditions or defining new business logic within theconnector. Lastly, event service 234 may use rules engine service 244 toevaluate semantic content of a message for message routing and also forpublication.

[0050] Data transformation service 246 is provided to perform bothsyntactic and semantic transformation of data. Examples of suchtransformations range from simple integer to character conversions totransforming the semantic content and meaning of a term during acollaboration. For example, a requirement to provide such a semantictransformation arises if “employee” in a first application hasassociated with it two fields (employee identification number (8 bits)and name), while “employee” in a second application has associated withit three fields (employee identification number (10 bits), name andsocial security number). When transferring employee data from the firstapplication to the second, two transformations might be used tosynchronize the two systems. One transformation would be required to mapemployee number (8 digit to 10 digit) and a second transformation wouldbe required to extract an employee's social security number from thefirst application's database and add that information into the secondapplication's system. Typically the targets for the transformations aredefined by the application collaboration module and the transformationsperformed in the connector. Connectors may also define transformationswithin their execution context, if necessary.

[0051] Transaction service 248 provides consistency across applicationslinked through the interchange server. Interchange server 20 provides atransaction model for supporting discrete asynchronous transactions withcompensating transactions. A compensating transaction is a transactionthat can semantically undo the effects of a previous transaction.Transaction service 248 includes one or more queues 249 (not shown), andmessage processor 250 (not shown) for implementing asynchronoustransactions. Transaction service 248 provides consistency acrossapplications in two ways. Store and forward queues manage transactionsdestined for applications that are not on line. Secondarily, transactionrecord queues are used to record transaction actions. The transactionrecord queues are used to recover from transactions that areinterrupted, so as to re-establish the state of the system prior to theexecution of the first action associated with an interruptedtransaction.

[0052] In one embodiment, sagas are used to maintain consistency andrecover from failures or other shutdowns received in the middle ofexecuting a transaction. A “saga” is a doubly linked list of connecteddiscrete transactions that consists of a set of steps (orsub-transactions) and compensating sub-transactions. To guaranteeconsistency, the present invention assures that either all thesub-transactions in a saga are completed or any partial execution isundone with compensating sub-transactions. Each sub-transaction in asaga does not assume the same consistent state. Therefore, once asub-transaction is complete, it can be committed without waiting forother sub-transactions of the same saga and thus release its results tothe rest of the concurrent transactions. In case of an interruption, anapplication collaboration module can attempt both forward or backwardrecovery of an interrupted transaction. Compensating transactions willbe discussed in more detail in association with the error and exceptionservice 260.

[0053] Referring now to FIGS. 3 and 5, in a method of maintainingconsistency in the interchange server, transaction service receives anotification that a transaction is to be initiated by an object, such asan application collaboration module in response to a event notification(500). When an application collaboration module receives notice of anevent, it initiates a saga initiation transaction request (or for thatmatter when any object in the interchange server initiates atransaction). Transaction service 248 responds to the saga initiationrequest by allocating a recording queue to store the actions associatedwith the transaction initiated by the application collaboration module(502). The transaction service 248 returns a saga identifier associatedwith the recording queue to the object initiating the transactionrequest (504).

[0054] Thereafter, the application collaboration module executessteps/actions according to its business interoperability function. Aseach action (also called transaction step) is initiated, the applicationcollaboration module generates a request for adding the step in theappropriate saga queue. The transaction service enters a loop and waitsfor the next request from the requesting object (506). The types ofrequests that can be received are add (508), delete (510), modify (512),get (514), undo (516) and end transaction (526).

[0055] If the next request is an “add” request, then the actionassociated with the “add” request is stored in the recording queue alongwith compensating transaction information (518). If the next request isa “delete” request, then the requested entry (action) from the queue isdeleted (520). If the next request is a “modify” request, then an entryin the queue is modified according to the request (522). If the nextrequest is a “get” request then the designated portions of the queue(saga) are returned to the requesting object (523). Finally, if the nextrequest is a undo request, a compensating transaction sequenceassociated with the actions stored in the queue is retrieved from sagaand initiated (524). At the completion of a transaction (upon receipt ofan end transaction request), the saga is removed (526-530).

[0056] In one embodiment, in the event a transaction is interrupted, acompensating engine within the transaction service executes compensatingactions to undo the saga stored in the recording queue associated withthe partially completed transaction. Aborting a transaction isaccomplished by executing a corresponding compensating transaction foreach action (sub-transaction) in the saga queue. The compensatingtransactions provide a logical or semantic “rollback” (since thetransaction has already committed). For example, the compensatingtransaction for “add employee” may be “remove employee”. However, thecompensating transaction may not be so simple. For example, a humanresources user may be mystified if a new employee simply disappearedfrom the system because some project tracking system, possibly locatedin another department in another location, rejected it. Accordingly,other more complicated compensating transactions are defined.

[0057] In an alternative embodiment, the transaction service within theinterchange server does not execute compensating transactions. Upondetection of a fault during the execution of a transaction resulting inthe need to roll back or roll forward as described above, thecompensating transactions stored in the saga record queues may beforwarded to individual connectors associated with the applications thatare a party to the transaction. Each connector in turn may be tasked toexecute the compensating transaction. Resources within the interchangeserver are not required to be tied up overseeing the execution ofcompensating transactions. Instead, each connector acts as a proxy forexecuting the appropriate compensating actions to undo the transaction.The connector logs into the application via the API to initiate theparticular undo transaction. Transactional consistency is effectivelydecentralized by delegating and enforcing at the connector level.

[0058] The transaction service is used to transfer compensatingtransactions to the connectors in the order of execution required toundo a transaction. The timing for when compensating transactions aretransferred and the form by which they are transferred may vary. Morespecifically, the storage of compensating transactions may bedecentralized such that the transaction service is not required to passcompensating transactions to the connectors after a fault is detected.As each transaction event is transferred to a connector (in response toreceipt of a trigger), compensating transaction information may beimplicitly or explicitly included for that particular transaction. Whena fault arises, the connectors can execute compensating transactionswhen prompted by the transaction system. Control for the timing of theexecution of compensating transactions may remain in the transactionservice.

[0059] As described above, compensating transactions may be explicitlyor implicitly provided with each transaction processed by a givenconnector. If the compensating transactions are explicitly provided, aqueue system may be included in the connector to store explicitcompensating transactions. Alternatively, in an implicit system, eachconnector is configured to associate a default compensating transactionwith each transaction that is processed by the connector. Defaultcompensating transactions may be hard-coded in the connector or may bedownloaded at initialization of the connector.

[0060] Note that compensating transaction information may be transferredto more than one connector depending on the complexity of the undorequirement for a given transaction. At the time a fault is detected,the transaction service may initiate recovery by indicating to therespective connectors which actions (subtransactions) are to be undone.As described above, the transaction system may pass the compensatingtransactions directly to the connectors after a fault is detected, orthe transaction system may merely indicate which transactions are to beundone (assuming compensating transactions have been implicitly orexplicitly identified for each transaction processed by the connector).

[0061] Alternatively, the transaction system may relinquish control ofthe roll back and roll forward operations by instructing a connector toundo a sequence of transactions. For example, the ordering of the undooperations at the connector level may be immaterial. In these types ofrollback situations, the transaction system may delegate the entirerollback operation to the connector level. The transaction system mayinstruct each connector to rollback all actions (subtransactions)associated with a particular transaction. Thus, transaction compensationcan be executed with the use of minimal transaction system resources.The use of a proxy service at the connector level to executecompensating transactions is described in greater detail below inassociation with FIG. 13.

[0062] In one embodiment, a 2PC (Two Phase Commit) coordinator is usedto coordinate the queuing of messages to multiple queues participatingin the application collaboration. When a single collaboration providesthe underlying messaging service to send messages to 5 applications, thetwo phase commit coordinator guarantees that either all the 5 messageswill be transmitted or none of the messages is transmitted.

[0063] Providing asynchronous transactional semantics in a connectorinvolves identifying transactional objects, its transactional methodsand providing the necessary functions (compensating transactions) tocompensate for these methods. The content of compensating transactionfunctions is collaboration specific implying that the processing logiccould be different for each method. In most cases, hand-coding thecompensating transactions will be required. In one embodiment, theinterchange server is able to dynamically enable and disable theexecution of the compensating transaction functions in any connector.

[0064] Error and exception service 260 provides notifications and hooksto handle errors. Error and exception service 260 provides anotification of any error identifying the component where the erroroccurred, location of such component, the nature of the error in theform of an error number and string. In the event a transaction isinterrupted, the error service issues a undo request to the transactionservice to initiate the “undo” actions stored in saga. Alternatively,the error and exception service may notify the appropriate applicationcollaboration module of the error. The application collaboration modulemay thereafter attempt both forward or backward recovery of aninterrupted transaction. In a backward recovery, the applicationcollaboration module issues an undo request to the transaction serviceto undo any transaction steps completed in the interrupted transaction.Alternatively, a forward recovery seeks to continue the interruptedtransaction by evaluating the particular error and deciding if it iscritical. If not, a work-around is employed.

[0065] The exception service allows users of the service to registerresources which can be de-registered easily in case of exceptions inprocessing.

[0066] Other services may be provided by interchange server 20including: a timer service, to let connectors and applicationcollaboration modules have pre-defined schedules for executing certainoperations; thread and synchronization service, to allow many operationsin the interchange server to be executed in parallel; licensing service;persistency service, to allow for persistently storing objects or objectstate outside that of an application; interface versioning service, todetect changed versions of the components interfaces; componentversioning service, for detection of changed components, such asconnectors which are upgraded or downgraded; other RAS feature servicesincluding upgrading, reporting and diagnosing bugs, performancemonitoring and tuning.

[0067] In one embodiment, interchange server 20 (and applicationcollaboration modules) are constructed in Java because of itscross-platform capability of execution. In one embodiment, the backboneof interchange server is a CORBA Object Request Broker (ORB) written inJava, produced by Visigenic, Co., Foster City, Calif., USA. The ORBoperates in a Java run-time environment. The necessary CORBA servicesare utilized from Java (using the IDL to Java generation, consisting ofJava stubs for the client and Java skeletons for the server).Communication transport in this scheme amongst interchange servers isIIOP (Internet inter orb protocol) or messaging. The communicationscheme between the two halves of the connectors or between interchangeservers and connectors can be IIOP or messaging.

[0068] A process flow for interchange server 20 is shown in FIG. 6.Referring now to FIGS. 3 and 6, at start-up, the interchange server isinitialized (600). The initialization includes retrieving configurationinformation from the repository associated with registry service 232including application collaboration module and connector information aswell as interchange services information. Thereafter a check is made todetermine if an error arose in the configuration (602). An error mayarise if there are configuration errors in a connector or applicationcollaboration module specification or if some service has invalid andunsupported options specified. If a critical error occurs (604), such asmessaging service not available, then the initialization halts (606).

[0069] If no error is detected or if the error is not critical (forexample, connector not having specified some properties but hasdefaults), then a check is made to determine if all of the service ininterchange server are available (608). If any critical services areunavailable (610), then the initialization terminates. Else, theinterchange server instantiates each installed and configured connector(612) and application collaboration module (614). Thereafter, theinterchange server enters a steady state loop waiting for servicerequests. Upon receipt of a service request (616), the interchangeserver checks to determine if the request is a shutdown request (618).

[0070] If so, the interchange server executes a shutdown procedure(620). If not, the interchange server services the request (622), andthen idles until the next request for service is received.

[0071] The servicing of requests is shown in more detail in FIG. 7. Arequest type is determined (700). If the request is an interchangeservice request branch A is invoked. If the request is a transactionrequest branch B is invoked. If the request is a management requestbranch C is invoked. Finally, if the request is a configuration requestbranch D is invoked.

[0072] In branch A, interchange service requests are processed by theappropriate interchange server service module in the interchange server(702) and a result is returned (704). For example, the request may be inthe form of an event notification. The event notification is received bythe event service and thereafter an object is distributed to each object(application collaboration module, connector or other interchangeserver) which subscribed to the particular event notification received.

[0073] In branch B, the type of the transaction request is determined(706). In one embodiment, the transaction types include a createtransaction saga (for creating a transaction saga queue), and sagaoperations (add, delete, return, or undo saga). If the request is acreate transaction saga (707), the transaction service allocates arecording queue for the new transaction and returns an identifier forthe saga (708). Alternatively, if the transaction received is a sagaoperation (709), the transaction service operates on the existing saga,and returns either an acknowledgment of the operation or executes acompensating transaction in response to an undo request (710).

[0074] In branch C, management requests are typed (712), and thereafteroperated on by the appropriate service (for example by the error andexception service) (714). In one embodiment, the management requestsinclude the logging of errors; starting, stopping, and passing ofobjects in the interchange server domain; performance data collection;and, event logging and diagnosis. Management requests can be generatedby objects within the interchange server or from a system managementtool through the system management interface 209 (FIG. 3).

[0075] In branch D, configuration requests are operated on by theconfiguration service. Configuration requests can be generated byconnectors, collaborations, interchange server objects or by theconfiguration tool. Configuration requests include the installation orremoval of application collaboration modules and connectors; activationor deactivation of connectors or application collaboration modules; andversion tracking and upgrade functions. The configuration serviceexecutes the configuration request (716) and returns an acknowledgment(or result) to the requesting object (or user) (718). Thereafter, theprocess continues at step 622 (FIG. 6), waiting for the next request forservice.

[0076] Referring now to FIGS. 3 and 8, the shutdown process (step 620 inFIG. 6) includes issuing shutdown requests to each applicationcollaboration module (800). A check is made to determine ifacknowledgment signals to the shutdown requests issued in step 800 havebeen received (802). Each collaboration responds to a shutdown requestby executing its own shutdown procedure. As part of this execution anacknowledgment signal is returned to interchange server 20. If anacknowledgment signal has not been received, then a check is made todetermine if a time out has expired (804). In one embodiment, the timeout is set to allow for the orderly shutdown of each component. A longtime out allows for the completion of tasks. If a time out is selectedthat is too short, some transactions executing in a component may beterminated prior to completion of a entire transaction, necessitatingthe execution of compensating transactions. Alternatively, the time outcan be set to a short time period to force an immediate shutdown of thesystem.

[0077] If the time out has yet to expire, the interchange server waitsuntil the receipt of the last acknowledgment or the expiration of theshortest timeout.

[0078] If the time out expires, interchange server (through theapplication collaboration module) initiates an undo transaction forservicing by the transaction service 248 (806). Thereafter, thetransaction service executes the compensating transactions required tomaintain consistency in the interchange server (807).

[0079] Upon receipt of the last acknowledgment or the completion of thelast compensating transaction, interchange server 20 generates aconnector shutdown for each instantiated connector (808). Each connectorresponds to a shutdown request by executing its own shutdown procedure.As part of this execution, an acknowledgment signal is returned tointerchange server 20. A check is made to determine if all theacknowledgment signals have been received (810). If an acknowledgmentsignal has not been received, then a check is made to determine if atime out has expired (812). In one embodiment, the time out is set toallow for the orderly shutdown of each connector. If the time out hasyet to expire, the interchange server waits until the receipt of thelast acknowledgment or the expiration of the shortest timeout.

[0080] If the time out expires or upon receipt of the lastacknowledgment signal, interchange server initiates an orderly shutdownof its own services and components (814).

[0081] Application Collaboration Modules

[0082] Typically, application integration is achieved through the“cooperation” of one application's objects with another application'sobjects. In the interchange server, application objects are representedas virtual objects by their respective connectors. These businessvirtual objects cooperate with other business virtual objects (fromanother application) and utilize facilities of “service” objects toperform the application integration function. This cooperation orinteraction amongst the various application objects defines and capturesthe application integration semantics and is encapsulated and stored inthe form of an application collaboration module in the interchangeserver. All multi-object application collaboration modules are storedand treated as a first class entity in the interchange server and arereferred to as an application collaboration object. The applicationcollaboration object encapsulates the business logic and businessprocess flow required to perform application integration.

[0083] Referring now to FIGS. 1, 3 and 9, an application collaborationmodule 40 includes a object representation module 900, a businessscenario module 902, and messaging communication module 904.

[0084] Application collaboration module 40 resides as an applicationcollaboration object in interchange server 20. An applicationcollaboration object identifies all participating interchange (connectorand “service”) objects and the “business scenarios” amongst theseobjects.

[0085] Object representation module 900 includes methods associated withthe application collaboration object including consume methods, receivemethods and object generation methods. This module also defines theabstracted re-usable classes and methods that are needed to participatein a given collaboration.

[0086] Messaging communication module 904 processes event notificationsand subscriptions. Event subscriptions are generated for transmission toevent subscription service 235. Event notifications are received fromevent publication service 236.

[0087] Business scenario module 902 includes a business scenariodefining a temporal ordering of message exchanges between cooperatingapplications. It also defines the reaction of these application objectsto such messages. Defining the business scenario includes identifyingthe participating attributes and methods for the collaboratingapplication objects. Object reaction behavior is described by a set ofdeclarative constraints and causal rules which may be enabledunconditionally or based on the state of the object.

[0088] All communication between applications is managed and enforced byapplication collaboration objects. Application collaboration objectsallow interchange users to define interactions between connectorobjects. One example of an application collaboration module isautomatically generating an invoice and adding the amount to theaccounts receivable entry in a financial system when a customer supportapplication logs a new support call.

[0089] An application collaboration object is defined by a set ofbusiness scenarios stored in business scenario module 902. Anapplication collaboration module has a single, business process orientedfunction. Several applicable collaborations may exist between any twoapplications, and collaborations may involve more than two applications.The single business process function may involve multiple transactions,also called scenarios. For example, an application collaboration modulewhich replicates employees across two or more applications would requirehandling hiring, firing, and status changes, all of which constitutedifferent scenarios for the same application collaboration module.

[0090] Application collaboration modules are controlled through propertysheets. Property sheets are the customers interface to control theconfiguration of an application collaboration module or any of itsparticipating application objects. Examples of application collaborationmodule properties are diagnostic level, user name/password, andintegration scenario specific properties. Properties of theparticipating application objects include setting the maximum, minimumand default values for any of the attributes of these applicationobjects, and the values of integration specific properties.

[0091] Since application collaboration objects are first class entities,they display typical object properties such as inheritance,polymorphism, etc. Application collaboration objects expose awell-defined interface in order to allow it to participate as anapplication object in another collaboration.

[0092] Referring now to FIG. 10, a message flow between objects for abill-by-call business scenario is shown in which the arrows from oneobject to another define the object interactions as ordered messageflows between these objects. A business scenario includes identifyingthe message flows, the participating application objects, theirattributes and methods, and the business rules associated therewith.Execution of any business scenario in an application collaborationmodule may typically be triggered by an event or message generated by aninterchange service object, a connector object or another applicationcollaboration object.

[0093] Referring again to FIG. 9, each scenario or set of objectinteractions is reduced and encapsulated into a Finite State Machine(FSM) 906. When triggered by an event, the FSM represents the processflow. To exert further control, events, conditions and actions can bemanipulated directly in the FSM to modify interaction behavior. The FSMassociated with each scenario is stored as an attribute for thatapplication collaboration object and is triggered by an event or messagesent to that application collaboration object.

[0094] FSM implementations may be decomposed such that “actions” in theFSM translate into one of the following mechanisms, based on location,transaction and performance requirements for the applicationcollaboration module and the participating application objects atexecution time. These mechanisms may include function dispatching (asimple local or remote function call), which is synchronous; messaging,which is similar to remote function dispatching except that it willperform asynchronous execution of the function (this is achieved bysending a message to a remote object with a request to execute somefunction using a reliable delivery capability of the messaging system);and event generation or state change within the same or another FSM. Thefunction calls may implement business rules for operating on attributesof objects, or data received through messaging or event services.

[0095] In one embodiment, application collaboration modules aregenerated in the Java language and extend the base collaboration Javaclass and interface (also known as sub-classing in object systems).

[0096] Referring now to FIG. 11, in a method for constructing anapplication collaboration module, an application collaboration modulebuilder defines a configuration of inter-related application objectsrequired to perform the cross-application integration (1100). Suchconfiguration should represent a single business process ranging from asimple to a more complex integration such as integrating a manufacturingschedule plan in a supply chain optimization application with an ERP(Enterprise Resource Planning) application. Defining this configurationincludes identifying the participating application objects (1102), theirattributes and methods required to perform the required applicationintegration (1104) and a “relationship” between the application objects(1106).

[0097] Thereafter the set of business scenarios driving the messageinteractions amongst the application objects within the applicationcollaboration module is identified (1108). Each scenario may represent abusiness process, a system management scenario, or a set of “business”transactions from the user's view. The set of all scenarios thatlogically perform participating functions in a single business processare grouped into one application collaboration module.

[0098] After defining the scenarios, the generic set of classes andtheir relationships which consolidate and abstract the structure andbehavior of the application objects is identified (1110).

[0099] Finally, the behavior is modeled (1112). The model may bedecomposed by dividing it into iterative steps to create a finergranular form if needed (1114). This allows iterative development suchthat the solution starts from the highest business model and iteratesdown to fine grained service objects as needed.

[0100] Application collaboration objects are re-usable acrossapplication objects derived from different vendors for the sameapplication class. This is achieved by having the applicationcollaboration object request the participating application object forthe required business behavior (method) and by not incorporating ordeveloping such behavior as part of the application collaboration objectitself. All such vendor specific functionality is encapsulated inconnectors, allowing the application collaboration module objects to bere-usable across different vendor's application for the same applicationclass.

[0101] Application collaboration objects are installed in theinterchange server using the set-up and configuration tools.Configuration tools allow setting the property sheets associated withthe application collaboration module such as setting the billing rate ina bill-by-call collaboration when that value is not available from anyof the participating applications.

[0102] In addition, application collaboration modules allow forconfiguration of various properties which control runtime and processingcriterion such as: instantiation characteristics (start-up or event);transaction semantics (synchronous 2PC with participating applicationsor asynchronous messaging with compensating transactions); executiontiming (scheduled and timed); and enablement (enable/disable) of anyparticipating business scenarios.

[0103] A process flow associated with application collaboration module40 (FIG. 1) is shown in FIG. 12. Referring now to FIGS. 3 and 12,application collaboration module receives an initialization request frominterchange server 20 as part of the instantiation process (1200). Theapplication collaboration module issues event subscriptions associatedwith the business scenario stored within the business scenario module(1202) and then returns an acknowledgment signal to interchange server20 in response to the initialization request (1204). Thereafter,application collaboration module waits for the delivery of a subscribedevent to trigger the beginning of a collaboration or an administrativerequest from the interchange server (such as a shutdown).

[0104] Upon receipt of an event notification (and associated object), orin response to an object received from interchange server 20 orapplication connector 30, business scenario module 902 (FIG. 9) executesthe methods called for in the object. If the object is an eventnotification (1207), the business scenario module requests a new sagafrom the transaction service (1208). Upon receiving a new saga requestacknowledgment from the transaction service, business scenario module902 (FIG. 9) initiates (1210) and executes (1211) the finite statemachine associated with the scenario stored within the business scenariomodule. At each sub-transaction within the scenario, business scenariomodule requests the transaction service to record the underlyingsub-transaction in the saga (1212). Thereafter, the business scenariomodule operates on the data received in the event notification (orobject delivery) (1214) and generates objects (by object representationmodule 900 of FIG. 9) for transmission to one or more applicationconnectors (1216). The process continues generating sub-transactionrequests and objects until an end of the scenario is reached (FSMexecution terminates) (1218) or a forced shutdown request is received(1220).

[0105] If the finite state machine has executed to termination, then afinal transaction request is generated and transmitted to thetransaction service to delete the saga stored therein (1222).Thereafter, a check is made to determine if a shutdown flag (either a“graceful” or Forced” shutdown flag) has been set (in steps 1230 and1233) (1223). If so, then a shutdown of the application collaborationmodule is initiated (1224). If not, then the process continues at step1206.

[0106] If a forced shutdown flag is set at step 1220, then a saga undorequest is issued to the transaction service (1226). Thereafter, theapplication collaboration module initiates its shutdown 1224.Alternatively, the application collaboration module may attempt tocomplete all transactions after a forced shutdown is received andthereafter invoke its own shutdown procedure at the completion of anyongoing transaction process.

[0107] If the object received at step 1207 is not an event notification,then a check is made to determine if the object received is a forcedshutdown request (1228). If so, a check is made to determine if a finitestate machine is executing in the application collaboration module(1229). If not, then application collaboration module will initiate itsshutdown procedure (1224). If a finite state machine is executing, thena “forced” shutdown flag is set (1230) and the process continues at step1206.

[0108] If the object received is not a forced shutdown request (step1228), then a check is made to determine if the object received is a“graceful” shutdown request (1231). If so, then a “graceful” shutdownflag is set (1233) and the process continues at step 1206. If not, thenthe object is in response to a request generated by the applicationcollaboration module due to the execution of an existing finite statemachine. Accordingly, the execution of finite state machine may beresumed (1232).

[0109] During operation, error and exception service 260 (FIG. 3),monitors the state of services and interchange server components. If anerror occurs, the error and exception service generates an error signalfor transmission to the application collaboration module. If the erroris fatal (e.g. the messaging service has failed), then the applicationcollaboration module initiates a backward recovery and then performs ashutdown. If the error is not fatal, then a determination is madewhether the collaboration needs to be terminated. If the collaborationis itself the source of the error, then the collaboration is required tobe shutdown and accordingly, a backward recovery is initiated followedby a shutdown of the application collaboration module. Alternatively, aforward recovery may be attempted if the error does not implicate theapplication collaboration module itself.

[0110] Collaboration Definition Tool

[0111] Collaboration builders are not required to write proceduralprograms to build collaborations. The collaboration definition toolreads the repository to get the business objects supported by installedconnectors and the generic class hierarchies available to collaborationdevelopers. This information is presented to collaboration developers ina visual, hierarchical form.

[0112] Collaboration developers may use these application classes andmodel them as objects using the supported object modeling methodology'svisual notations. The application integration scenarios may be modeledby drawing lines and arrows to signify message exchanges amongst theapplication objects available and by picking from a list of supportedmethods (corresponding to application objects), the method to invoke asa reaction to a received message along with appropriate arguments.Business rules and constraints are defined through the use of anintegrated rules definition table and incorporated into the businessscenario diagrams at well-defined anchor points. Any datatransformations, if needed, are similarly defined using adata-transformation tool with hooks to anchor in such transformationsinto the application integration scenario. Collaboration developers arethus able to build the entire collaboration using visual tools. Anexample is shown in FIG. 10. This is just a sample visualization, theactual visual will depend on the object modeling methodology supportedby the modeling tool.

[0113] After the collaboration has been visually modeled and all partsof it is defined, the collaboration definition tool reduces the businessscenarios into a finite state machine and generate configurationinformation and Java class files. All collaboration configuration,including details of participating objects/classes, their attributes andparticipating methods, relationships between the objects, the finitestate machine, configured properties such as locational, execution andtransactions semantics, etc. are stored in the repository duringcollaboration installation. The supporting Java class files depictingthe collaboration and generated by the collaboration definition tool arestored in a well-defined location and a path to this is stored in therepository.

[0114] The application collaboration module, once installed can beconfigured and managed by other interchange tools as needed. Forcollaborations that require new business objects, programmatic tools areavailable to let such objects be created and built either by using theconnector development toolkit (if new objects are to come from aconnector) or by writing Java code, if the object is local to acollaborator.

[0115] Connectors

[0116] Connectors interface between the interchange server and businessapplications. Each connector is application area and vendor specific.The connector utilizes the application's API, and transforms data andoperations in the application to and from the interchange server'sobject and event model. For example, a human resources (HR) applicationmay have the concept of an employee, and mechanisms for adding employeesand changing their salary. The corresponding application connectorprovides a representation of the employee in the interchange server'sobject model. It is the responsibility of the connector to detect andkeep track of changes in the application, and if necessary issue events.

[0117] Connectors manipulate the application API's to extractinformation from and deposit information to the application. Informationin this context means both data and function.

[0118] Connectors represent the data and function from an application ininterchange server as an application object. The application objectmodel follows the base object model defined by the interchange server.

[0119] Connectors also bridge any semantic and syntactic gaps betweenapplication's data and behavior and its representation in theinterchange server. This involves performing appropriate datatransformations and implementing behavior semantics needed to presentapplication data and behavior into the defined object model.

[0120] Connectors may incorporate vendor/application specific businessrules and logic (constraints) needed to provide the correct behavioralsemantics expected or desired by a particular application collaborationmodule. For example, an application collaboration module may desire toreceive data relating to customers only from the “North American” regionwhile the application may not distinguish between customers in regions.In such cases, the connector may be tailored to include business logicto only pick up those customers which fall in the “North American”region.

[0121] The business logic provides filtering at the source of data entryinto the collaboration model. Rather than requiring all data of aparticular type (customers from across the world) to be received and beprocessed at the collaboration level, the connector business logic canbe effectively used to pre-screen all incoming data to assure a matchwith the needs and wants of a particular collaboration. Filtering at thesource frees up interchange server resources by minimizing the trafficof data to a collaboration to be exactly of the type requested withoutregard for the support of the particular data distinction at theapplication level. Filtering at the source may also be used todistribute events across multiple interchange servers to achieve loadbalancing, deploying across geographically distributed topologies andenforcing business logic.

[0122] Filtering at the source may be realized by including the businesslogic in the connector level to pre-screen event data. Collaborationsmay thereafter provide precise event subscription information to thesubscription service that includes the desired filter. The filterinformation may be hard-coded at the time the connector is constructedby the developer. Alternatively, the filter information may betransferred to the connector at intitialization or dynamically updatedover time. During the initialization process, the connector downloads adefinition for all objects (business objects) that it will support. Therepository in the interchange server includes meta-data providingdefinitions for objects which are supported by a given connector. Abusiness object definition may include an attribute which defines thefilter function. For example, a connector may be required to support adelete employee business object which includes an attribute “OVER65”that indicates that only employees with ages over 65 are to be deleted.The filter information (attribute OVER65) may be used by the connectorto screen events for transmission to the interchange server. A meta-datamanagement service associated with each connector is used to retrievethe object definition information for each connector from the repositoryfor use by the connector. The meta-data management service may be usedto dynamically update objects after the connector initialization phasein support of run-time business collaboration execution requirements.

[0123] Connectors may provide application and/or vendor specificfunctionality needed by an application collaboration module, which isnot provided by the application, by incorporating it within theconnector. An example here is a financial accounting system which doesnot provide a billing function. For a bill-by-call applicationcollaboration module, such a billing function is incorporated in theconnector for the financial application.

[0124] Connectors provide event notifications to applicationcollaboration modules and interchange servers when changes inapplications occur. Other functions provided by the connectors includeerror handling and communication “middleware” (to communicate with theinterchange server for in-process, out-of-process and over local andwide area network topologies). Connectors may also support managementinterfaces to allow management tools to manage the connector as anyother component, install, setup and configure connectors, and providesecurity (for secure transactions between connectors and the interchangeserver). In addition, connectors may include a proxy service includingcompensating transaction queues for executing compensating transactionsas described above.

[0125] Referring now to FIG. 13, a connector 30 includes an APImanipulator 1300, a data transformer 1302, a business rules andconstraint module 1304 including meta-data management service 1305, abusiness encapsulation module 1306, a message transformer 1308, acommunication module 1310, an object representation module 1312, aconfiguration tool set and management interface 1314 and error handler1316. A connector 30 may also include proxy service 1317 includingcompensation queue 1319.

[0126] Typically, an application connector does not interact directlywith the application's data which may be residing in a Data BaseManagement System. Instead, the interchange operates against vendorsupplied API's using an application specific API manipulator 1300. Thisallows all connector operations to run against the application's ownprocessing logic, thereby reducing the dependency on the applicationvendor's internal logic and schema changes. For example, in a customersupport application, adding a new customer in a customer table requiresthat the customer agreement information (billing rate, support level,24×7 support information, etc.) be updated in an agreement table. APImanipulation is the most vendor (and application) specific part in anyconnector and is layered at the bottom of the connector's logical stack.

[0127] Connectors provide bi-directional syntactic and semantictransformations when going from applications', data and function intothe interchange server object model and vice-versa. These functions areprovided by the data transformer 1302, the business rules andconstraints module 1304 and business encapsulation module 1306.

[0128] Data Transformer 1302 transforms the application data andfunction to a data format suitable to the connector. Data transformerincludes an interactive tool 1320 to visually define the data formatsfor transformation, which will be bundled with the connector developmenttool, and a runtime component 1322 which performs the actualtransformations and is embedded in the connector executable code.Interactive tool 1320 describes the input and output formats andappropriate conversions. These conversions range from implicit syntacticconversions to semantic-content based conversions. The tool providesmathematical (+, −, *, /, . . . ), string (truncate, append, etc.),logical (>, <. >=, etc.) and boolean (AND, OR, NOT, etc. operators whichwork on the contents of input and output fields. It also provides hooksto incorporate foreign language functions, if needed. Examples offoreign language functions are functions that may read an external tablefrom a different data source such as a flat file for validatinginformation. Typically, data transformations are performed as soon asthe data is read from the application or just before the data is writteninto the application, or, depending on the application collaborationlogic, may be performed in different points in time for a givenconnector.

[0129] Business rules and constraints module 1304 includes a tool todefine a set of rules 1330 which contain the information necessary toenforce vendor specific business rules and a rules engine 1332. Therules engine 1332 evaluates the rules. Meta-data management service 1305downloads definitions for all objects that are to be supported by aconnector. As described above, attributes for a particular object maydefine a filter to be used by the connector. The filter is stored as arule for processing by rule engine 1332. For example, a businessapplication may provide business records for customers from across theworld. A collaboration may only require the records associated with aparticular geographical region. The business encapsulation moduleprovides a screen to filter such records and only provides thoseappropriate records as objects to the application collaboration moduleby having a business rule (stored in the set of rules 1330) whichfilters such records.

[0130] Business encapsulation module 1306 adds business functionalitywhich is not provided by the application but is required by theapplication collaboration module. For example, if a customer supportapplication does not keep track of the accumulated time for all supportcalls logged against a case, then the business encapsulation module 1306is used to accumulate and store persistently the time logged against acase by totaling the time for each support call in the database asrequired to provide the business functionality desired.

[0131] Event notifications initiate processing in an applicationcollaboration module. Events are also used to communicate changesbetween various components. Events are generated from connectors toallow applications to communicate modifications in the application'sdata to the interchange server. Connectors keep track of changesoccurring within the application and communicate them through events tothe interchange server.

[0132] Connectors rely on persistent event notification fromapplications by having connectors queue them into a reliable messagingsystem to prevent loss of such events in case of failure within thecomponents. In case of connector failure, the connector determines andcommunicates to the interchange server all changes that occurred afterthe connector failed. The message transformer 1308 and communicationmodule 1310 provide the message oriented middle-ware (MOM) to transportmessages within connectors as well as between connectors and interchangeservers. A similar mechanism is used in interchange servers. Messagingmiddle-ware provides the asynchronous semantics needed by the executionenvironment to support inter-operability between geographicallydistributed applications by providing sequential queuing with reliabledelivery. This provides assurance that applications do not wait foracknowledgments over slow wide area networks and they can continue doingwork. The underlying assumption is that the message queued to a remotesystem will definitely be delivered. MOM also provides the semantics forhandling instances when the application is unavailable by queuing theirmessages to a persistent store. When the application starts up again itretrieves its messages from the store, in the correct order, andprocesses them. This MOM implementation also provide time-outs onmessages in order to expire messages and generate errors requiringtransaction abort and recovery in the collaboration.

[0133] Object representation module 1312 builds object wrappers aroundthe application's data and behavior and present it using the interchangeserver's base object model. The wrappers provide a framework toaccurately represent the application's data and function schema asrequired by the application collaboration module, irrespective ofwhether such data and function reside in the application or theconnector itself. Wrappers also interpret the generic framework andrepresent the framework contents in the interchange server's base objectmodel. This is a bi-directional mechanism which also converts from theinterchange server's object model into the framework for execution inthe connector. Finally, the wrappers provide semantic content in aspecific wrapper or framework, which describes the meaning of a givenapplication object, such as what are its attributes and its functionsand what do they do.

[0134] In one embodiment a proxy service 317 is included in connector30. Proxy service 317 may include methods for logging actions associatedwith a transaction and for storing compensating transactions associatedtherewith in a compensation queue 319. Each action received may includeexplicit or implicit compensating transaction information. Compensationqueue 319 may include a plurality of individual transaction queues onefor each transaction active in a given connector. Each transaction queueis configured as a FIFO (first-in-first-out), allowing for thesequential rollback of actions based on receipt at the connector. Proxyservice 317 is responsive to objects received from the interchangeserver to rollback individual ones of actions stored in a respectivetransaction queue or may initiate rollback of an entire queue. At thecompletion of a rollback, proxy service 317 provides an eventnotification to the interchange server to indicate the success (orfailure) of a compensating transaction (or individual compensatingaction).

[0135] In one embodiment, connectors are built using any language andare exposed to the interchange server using Java wrappers, CORBA IDL orMicrosoft's OLE/Activex technology. Interchange server provides hooksfor invoking (tying in) components in any of the above stated forms. Abase connector class/interface is defined which is extended to providebase classes for the 3 types (Java, IDL and OLE/Activex).

[0136] Application objects are represented by their class definitions atthe time of application collaboration module creation. It is only atrun-time that application objects are instantiated by the connector asvirtual objects. Application collaboration objects are independent ofthe participating application's platform of execution. Minimally, theyexecute on the same platform on which the interchange server executes.

[0137] Error handler 1316 synchronizes with management interfaces,logging facilities and error handling services in other components.Configuration tools 1314 support various management interfaces. Theseinterfaces adhere to platform specific management interface standards sothat existing management tools are able to manage the connector process.Configuration tools also allow for the installation of applicationconnectors.

[0138] An application connector is a component which operates like an“object factory”. This means that it supports an interface that can dothings like “create object”, “get object”, “destroy object”. Theseobjects include connector, application and virtual objects. Theyrepresent objects, data, and services provided by the application,collaboration or server. In many cases, these objects are “proxy”objects. They represent remote objects but don't actually contain anyobject state.

[0139] When the interchange server needs to access a connector object,it gets a “handle” to that object. From the perspective of aninterchange server, any object presented by a connector is similar inthat the interchange server does not care where exactly that objectresides (data and function). Neither does it keep track of stateinformation for connector objects. State information for the object, ifnecessary, is maintained by the connector. If the collaboration needssome state of a connector object, then it creates a local object whichis a snap-shot copy of the connector object and uses that for localprocessing. Collaborations cannot rely on connectors to maintain anyobject state information unless explicitly required for transactionalconsistency. In one embodiment, connector objects are cached to speedperformance of the collaboration process.

[0140] Each application connector supports a set of pre-defined object“types” that it knows how to deal with. An HR application, for example,supports an employee type. A customer service application supports acustomer type. All application connectors are required to support aminimal set of facility object types for the purpose of providingrequired services, for example an event service type, an event type, atransaction service type, a transaction type, a receive method, aconsume method, etc. In one embodiment, the object representation moduleuses an event-based publish and subscribe mechanism in lieu of lookingat events just from a service perspective, thus events are just anotherform of business object which are published and subscribed to.

[0141] When an object is received either due to an event subscription orin response to the invoking of a consume method, a connectorcommunicates with the application, retrieves the data necessary toconstruct the requested object (for example, generate queries to adatabase), applies the necessary data transformations, rules andbusiness logic, constructs the object, and returns a handle to theobject to the requester/subscriber by invoking the requester'sreceiveDelivery or consume methods.

[0142] The connector communicates with the application by either callingthe application API directly, or by communicating with a gateway processwhich in turn, calls the application API. Such communication can beachieved more efficiently using an event based publish-subscribemechanism.

[0143] Events in the interchange server may be external or internal.Internal events are those generated by the services within theinterchange server such as application collaboration modules, timers,synchronization primitives, other services. External events are thosegenerated by external components such as connectors or other interchangeservers.

[0144] Referring now to FIGS. 13 and 14, a process flow for connector 30is shown. At initialization, connector 30 publishes a list of eventsthat it is responsible for in each collaboration (1400). The connectorthen subscribes to events according to its associated business scenarioby providing an event subscription via message transformer 1308 to theinterchange server (1401). Thereafter, the connector waits for receiptof information from either the application or the interchange server.Information from the application may take the form of event triggeringinformation or information returned from the application responsive to arequest for information from an application collaboration module.Information from the interchange server may take the form of a businessobject request from the application collaboration module or the returnof a requested business object from the collaboration based on asubscription by the connector. If application information is received bythe connector (1402), data transformer 1302 converts the informationinto the appropriate format for business rules and constraints module1304 (1406). Business rules and constraints module 1304 executes a runtime evaluation of the associated rules to incorporate the specificvendor/application semantics expected by the application collaborationmodule (1408). The event may be screened out at this step and notprovided to the interchange server, depending on filter information thatmay be present in the rules. If the information is to be passed on tothe interchange server, business encapsulation module may add anyrequired business functionality which is not provided by the applicationbut is required by the application collaboration module (1409).

[0145] Thereafter an event notification is generated by messagetransformer 1308 (1410) and an appropriate object is created accordingto the interchange object base model by the object representation module1312 (1412). The object and event are transferred as a business objectto the application collaboration module by the communication module 1310via the interchange server (1414).

[0146] If interchange server information or requests are received, suchrequests (or responses to requests) is processed by message transformer1308 (1416) and the object is transformed into the appropriate formatfor the connector by the object representation module 1312 (1418). Theencapsulation module adds any functionality that is required at theconnector level (1420). Thereafter, the business rules and constraintsmodule 1304 executes a run time evaluation of the associated rules toincorporate the specific vendor/application semantics expected by theapplication (1422). Data transformer 1302 converts the information intothe appropriate format for API manipulator 1300 (1424), which in turntransfers the information to the application (1426). The informationreturned to the application may be in the form of data to be manipulatedby the application or a request for data to be used in thecollaboration.

[0147] This process continues until a shutdown request is received. Ashutdown request may include a compensating transaction, or may onlyrequire the shutdown of the connector. Upon receipt of a shutdownrequest, connector 30 performs any compensating transactions receivedfrom the exception service or an application collaboration module theninitiates its own shutdown procedure.

[0148] Administrative Tools and Interfaces

[0149] Referring now to FIG. 15, administrative tools 50 (FIG. 3)includes an installation tool 1502, set up tool 1504, a configurationtool 1506, and management interfaces 1508.

[0150] Installation tool 1502 is used for installing, collectingrequired parameters, and removing components in the interchange server.The installation tool is meta-data driven such that the information thatguides the tool is stored in the components themselves, rather thanbeing known intrinsically by the tool.

[0151] The setup tool 1504 installs a component into any interchangeserver within its administrative domain.

[0152] Configuration tool 1506 is also a meta-data driven tool forviewing and changing the configuration of installed interchange servers,application collaboration modules and connectors. In addition toconfiguration, it also allows customers to enable or disable executingcomponents. Configuration meta-data is stored as properties in theinterchange objects (objects which have configurable propertiesinherited from a base class that provides the configurable propertybehavior). A property provides a name, a data type, default value, andrules for allowable values. Configuration tool 1506 performs automaticversion management when revising (or originally configuring) versions ofparticipating applications. When upgrading to a different version of aparticipating application, the configuration tool will determine if anyother components are required or if alternative action has to beperformed.

[0153] Management interfaces 1508 are also meta-data driven. Themeta-data populates a standard interface such as SMS or SNMP. Standardsystem management tools are used to access those interfaces. There aretwo kinds of administrative interfaces: resource administration (whichservers are up, show me the threads, show me memory utilization, tell mewhen the log is x % full, etc.) and integration operationadministration. The former are provided through the support of standardadministration framework hooks.

[0154] Development Tools

[0155] Referring now to FIG. 16, development tools 60 (FIG. 3) include aconnector development kit 1600 that enables customers and vendors tobuild their own connectors. This will be particularly useful forcustomers who wish to integrate home-grown applications with theinterchange. The connector development kit includes interchangeprotocols and API's 1602, a connector framework 1604 (which wouldprovide a set of classes in the form of source code), a packager forpackaging the connector as a component 1606 and rules and datatransformation tools 1608.

[0156] Bill by Call Collaboration

[0157] A practical example of a collaboration is a “bill-by-call”application collaboration module where a call tracking (customersupport) application, upon completion of the call, sends a request to abilling application to generate and send an invoice to the customer. Thebusiness process interactions between the call tracking application andthe billing application are through a bi-directional exchange ofmessages. For the call tracking application, the data required is theCustomer ID, Name, Address and Billing Rate. The business functionalitydesired consists of CalcCallDuration (to calculate Call Duration) andtellNameAddressid (to get the Callers Name, Address and Customer ID)from the call tracking application.

[0158] The data required for the billing application is Customer ID,Billing Address, etc. The business functionality desired areVerifyCustDetails (to determine if this is a valid customer) andGeninvoice (to generate and send the invoice to the customer). Themessage flows associated with this type of collaboration are shown inFIG. 10.

[0159] Although simple at one level, the above application collaborationmodule can actually be quite complex under diverse conditions such as(a) when the Customer IDs in the two applications are not similar or (b)when the billing rate may be provided by either the call trackingapplication, the billing application or the application collaborationmodule itself. Using the configuration tool, the user may set morespecific options, such as: how to round the call duration; or to specifyif it is a fixed charge per call or charged per minute; whether callsare billed individually or lumped together; to determine if the callergets a certain amount of support free; and to identify who provides therate of billing (one of the applications, the application collaborationmodule or if it is derived from somewhere else).

[0160] The installation and configuration process sets properties oninterchange server's objects and adds those entries to the repository.The repository also maintains information on the existence and locationof the two connectors and the application collaboration module. When theinterchange server boots, it contacts the repository and finds out whatcomponents it's supposed to start up. In this case, it would be the twoconnectors and the one collaboration. The boot process would start upthese components and then exits. When a component starts up, it consultsits properties to determine its startup parameters. In the case of theconnectors, the parameters would include the network location of theapplications to be connected to, and information about how thoseapplications were customized. In the case of the collaboration, thestartup properties include things like which connector to use, when toinstantiate the application collaboration object (start-up oron-request), etc. Note that the identity of the connector is specifiedas a name in a registry in order to preserve location transparency.Similarly application collaboration objects will have a name in theregistry in order to let other interchange server's access that objectdirectly.

[0161] The call tracking application connector presents anobject-and-event oriented interface to the interchange. For the sake ofthis example, imagine that the objects are Product, Customer, Case, andCall. Events might be NewCase, CallCompleted, and CaseClosed. An exampleof one of the methods supported by the call tracking connector would beReturnCaseHistory which returns information on all calls and on theduration of each for any given case.

[0162] Similarly, the billing connector provides a billing object whichexposes the accountsReceivables, and billAccount methods. Note, that wehave separated out the accountsReceivables method in order to maximizeflexibility. This method updates the invoice information in the accountsreceivable system. In most cases customers will want to control whichbills are automatically inserted into accounts receivable. ProvidingaccountsReceivable as a separate method simplifies the need to make theautomatic insertion of bills into accounts receivable user controllable.In cases where the bill is to be inserted, the method is invoked. Incases where the insertion should not be performed, the method is notused.

[0163] When the interchange server boots up, it first instantiates allconnectors, followed by all application collaboration objects. Atinstantiation, the billing application's connector subscribes to thecall tracking connector's CaseClosed event (assuming that the system isnot supposed to generate a bill until the case is closed). The calltracking connector generates a CaseClosed event when the support analystcloses the case by setting the status of the case to CLOSED. Uponreceiving the CaseClosed event, the collaboration object queries thecall tracking connector for all the calls for that case and theirduration by invoking the ReturnCaseHistory method on the case number inquestion. The returned call duration is converted into a dollar amountaccording to the business rules specified by the applicationcollaboration object's properties. It might also have to query the calltracking connector to translate Customer ID to a customer name or it mayhave to map the Customer ID in the call tracking application to theCustomer ID in the billing application.

[0164] The collaboration object then invokes the billAccount functionfor the billing object in the billing connector, passing it the customername, the dollar amount, and a text string describing the calls and thecase. Successfully generating the bill will probably require multipledata conversions. Translating the customer's name into the Financialsystem's Customer ID might be necessary and there may be currencylocalization issues to address with regards to the representation of thedollar amount. Since these conversions need to be addressed prior to theactual submission of the billing information into the accountsreceivable application, the collaboration object needs to be able tohandle conditional data conversions, based on a pre-determined set ofdynamically determined business rules.

[0165] Once all data translation steps have been processed, thecollaboration can invoke the accountReceivables function in the billingconnector to update the “just billed” amount to the accounts receivable.

[0166] The present invention has been described in terms of specificembodiments, which are illustrative of the invention and are not to beconstrued as limiting. Other embodiments are within the scope of thefollowing claims.

What is claimed is:
 1. A modular application collaborator for providinginter-operability between applications comprising: a plurality ofconnectors for communicating with a like plurality of applications; aninterchange server including an application collaboration moduleincluding a collaboration defining the inter-operability between two ormore applications and a service module including a transaction systemfor transferring information between connectors and the applicationcollaboration module, the service module including a transaction serviceand an error service, the transaction service for recording each actionexecuted during run-time for the collaboration and a compensatingaction, the compensating action for undoing an associated action, theerror service for monitoring errors in the execution of thecollaboration and upon detection of an error stopping the execution ofactions and triggering the execution at the connectors of any requiredcompensating actions to undo actions previously executed.
 2. Theapparatus of claim 1 wherein each connector includes a business moduleincluding business methods and transforms for screening data fortransfer between an associated application and an applicationcollaboration module.